Astronaut Pam Melroy, SM ‘84, had traveled to space twice before. But last October 23, she boarded the space ­shuttle Discovery in charge of a mission to transport what NASA calls a “high-tech hallway and Tinkertoy-like hub” to the International Space Station. On her watch, the crew would perform multiple space walks to deliver the hub; the crew would also move a giant truss element holding solar arrays to a new position on the space station and redeploy the arrays. The mission would enable the European Space Agency and the Japan Aerospace Exploration Agency to attach new laboratories to the space station, significantly expanding its size and research capacity.

Halfway through the 15-day mission, former president George H.W. Bush and Barbara Bush called Melroy and the shuttle and space-station crews to congratulate them on the successful installation of the hub. The video of the call shows crew members assembled in a circle as Melroy and space-station commander Peggy Whitson speak to the Bushes with as much gravity as is possible in microgravity. What it doesn’t show is any evidence of the high-altitude high jinks that had just taken place.

Right before the Bushes arrived at Houston’s command central, the astronauts had spontaneously disappeared into hiding spaces. Melroy explains that the newly installed hub was empty, completely equipment free. “There were these indentations where you could hang out right next to the camera so you wouldn’t be seen,” she says. “The capcom [capsule communicator] started to get nervous. Time was ticking, and it was 30 seconds to the time the president was going to come in, and the room was empty as far as he could tell from the camera. The capcom said, ‘Uh, I think you might want to start thinking about getting ready.’ And we burst from our hiding places and were all neatly assembled in our positions in 20 seconds. He said, ‘Oh, you guys got me good.’”

Humor, Melroy discovered early on, was the linchpin that would hold her team together. Space travel may be an adventure, but it’s a high-stakes, high-pressure adventure fraught with danger. One wrong decision could foil the mission’s goals–or kill the entire crew. And train as you might, there is no earthly equivalent of the chaos and uncertainty found 122 nautical miles above the planet.

A sea kayaking expedition in Alaska comes close, however. So Melroy, a retired U.S. Air Force colonel who flew in Desert Shield/Desert Storm, assembled her crew in Alaska, where the astronauts traded a high-tech command-control interface and pressurized space suits for paddles and life vests.

The training exercise challenged the astronauts physically and let them practice living, problem-solving, and working together. Crew chemistry is always a big unknown in space missions; astronauts are chosen for their skills, not necessarily for how they’ll gel as a team. “It can have a big impact on performance in orbit if people are not getting along,” Melroy explains. “It’s very important to acknowledge that it’s an extremely stressful job. We’re the only ones who really understand what the other is going through.” On the rough Alaskan waters, she quickly learned that her team loved to laugh together.